High efficient delivery of a large therapeutic mass aerosol

ABSTRACT

A method for delivering a therapeutic dose of a bioactive agent to the pulmonary system, in a single, breath-activated step, comprises administering from a receptacle enclosing a mass of particles, to a subject&#39;s respiratory tract, particles which have a tap density of less than 0.4 g/cm 3  and deliver at least about 50% of the mass of particles. Another method of delivering a therapeutic dose of a bioactive agent to the pulmonary system, in a single breath, includes administering from a receptacle enclosing a mass of particles, to a subject&#39;s respiratory tract, particles which have a tap density of at least 0.4 g/cm 3  and deliver at least about 10 milligrams of the bioactive agent. The receptacle can have a volume of at least 0.37 cm 3 .

BACKGROUND OF THE INVENTION

Aerosols for the delivery of therapeutic agents to the respiratory tracthave been described, for example, Adjei, A. and Garren, J. Pharm. Res.,7: 565-569 (1990); and Zanen, P. and Lamm, J.-W. J. Int. J. Pharm., 114:111-115 (1995). The respiratory tract encompasses the upper airways,including the oropharynx and larynx, followed by the lower airways,which include the trachea followed by bifurcations into the bronchi andbronchioii, The upper and lower airways are called the conductingairways. The terminal bronchioli then divide into respiratory bronchioliwhich then lead to the ultimate respiratory zone, the alveoli, or deeplung. Gonda, I. “Aerosols for delivery of therapeutic and diagnosticagents to the respiratory tract,” in Critical Reviews in TherapeuticDrug Carrier Systems, 6: 273-313 (1990). The deep lung, or alveoli, arethe primary target of inhaled therapeutic aerosols for systemic drugdelivery.

Inhaled aerosols have been used for the treatment of local lungdisorders including asthma and cystic fibrosis (Anderson Am. Rev.Respir. Dis., 140: 1317-1324 (1989)) and have potential for the systemicdelivery of peptides and proteins as well (Patton and Platz, AdvancedDrug Delivery Reviews, 8: 179-196 (1992)).

Relatively high bioavailability of many molecules, includingmacromolecules, can be achieved via inhalation. Wall, D. A., DrugDelivery, 2: 1-20 (1995); Patton, J. and Platz, R., Adv. Drug Del. Rev.,8: 179-196 (1992); and Byron, P., Adv. Drug. Del. Rev., 5: 107-132(1990). As a result, several aerosol formulations of therapeutic drugsare in use or are being tested for delivery to the lung. Patton, J. S.,et al, J. Controlled Release, 28: 79-85 (1994); Damms, B. and Bains, W.,Nature Biotechnology (1996); Niven, R. W., et al., Pharm. Res., 12(9):1343-1349 (1995); and Kobayashi, S., et al, Pharm Res., 13-(1): 80-83(1996).

However, pulmonary drug delivery strategies present many difficulties,in particular for the delivery of macromolecules; these include proteindenaturation during aerosolization, excessive loss of inhaled drug inthe oropharyngeal cavity (often exceeding 80%), poor control over thesite of deposition, lack of reproducibility of therapeutic results owingto variations in breathing patterns, the frequent too-rapid absorptionof drug potentially resulting in local toxic effects, and phagocytosisby lung macrophages.

In addition, many of the devices currently available for inhalationtherapy are associated with drug losses. Considerable attention has beendevoted to the design of therapeutic aerosol inhalers to improve theefficiency of inhalation therapies. Timsina et. al., Int. J. Pharm.,101: 1-13 (1995); and Tansey, I. P., Spray Technol Market, 4: 26-29(1994). Attention has also been given to the design of dry powderaerosol surface texture, regarding particularly the need to avoidparticle aggregation, a phenomenon which considerably diminishes theefficiency of inhalation therapies. French, D. L., Edwards, D. A. andNiven, R. W., J. Aerosol Sci., 27: 769-783 (1996).

Dry powder formulations (DPF's) are gaining increased interest asaerosol formulations for pulmonary delivery. Damms, B. and W. Bains,Nature Biotechnology (1996); Kobayashi, S., et al., Pharm. Res., 13(1):80-83 (1996); and Timsina, M., et al., Int. J. Pharm., 101: 1-13 (1994).Dry powder aerosols for inhalation therapy are generally produced withmean geometric diameters primarily in the range of less than 5 μm.Ganderton, D., J. Biopharmaceutical Sciences, 3: 101-105 (1992); andGonda, I. “Physico-Chemical Principles in Aerosol Delivery,” in Topicsin Pharmaceutical Sciences 1991, Crommelin, D. J. and K. K. Midha, Eds.,Medpharmn Scientific Publishers, Stuttgart, pp. 95-115, 1992. Large“carrier” particles (containing no drug) have been co-delivered withtherapeutic aerosols to aid in achieving efficient aerosolization amongother possible benefits. French, D. L., Edwards, D. A. and Niven, R. W.,J. Aerosol Sci., 27: 769-783 (1996).

Among the disadvantages of DPF's is that powders of fine particulatesusually have poor flowability and aerosolization properties, leading torelatively low respirable fractions of aerosol, which are the fractionsof inhaled aerosol that deposit in the lungs, escaping deposition in themouth and throat. Gonda, I., in Topics in Pharmaceutical Sciences 1991,D. Crommelin and K. Midha, Editors, Stuttgart: Medpharm ScientificPublishers, 95-117 (1992). Poor flowability and aerosolizationproperties are typically caused by particulate aggregation, due toparticle-particle interactions, such as hydrophobic, electrostatic, andcapillary interactions. Some improvements in DPF's have been made forinstance. Dry powder formulations (“DPFs”) with large particle size haveimproved flowability characteristics, such as less aggregation (Edwards,et al., Science 276:1868-1871 (1997)), easier aerosolization, andpotentially less phagocytosis. Rudt, S. and R. H. Muller, J. ControlledRelease, 22: 263-272 (1992); Tabata, Y. and Y. Ikada, J. Biomed Mater.Res., 22: 837-858 (1988). An effective dry-powder inhalation therapy forboth short and long term release of therapeutics, either for local orsystemic delivery, requires a method to deliver DPF to the lungsefficiently, and at therapeutic levels, without requiring excessiveenergy input.

Nebulizers, such as described by Cipolla et al., Respiratory DrugDelivery VII, Biological, Pharmaceutical, Clinical and Regulatory IssuesRelating to Optimized Drug Delivery by Aerosol, Conference held May14-18, 2000, Palm Springs, Fla., the contents of which are incorporatedherein by reference in their entirety, also are employed in pulmonarydelivery.

Inhalation devices which can be employed to deliver dry powderformulations to the lungs include non-breath-activated or “multistep”devices. One such device is described in U.S. Pat. No. 5,997,848 issuedto Patton et al. on Dec. 7, 1999, the entire teachings of which areincorporated herein by reference. In these devices, the drug formulationis first dispersed by energy independent of a patient's breath, theninhaled.

Inhalation devices that utilize a “single, breath activated-step”disperse the powder and inhale it at the same time, i.e., in a singlestep, for example, a simple dry powder inhaler. (U.S. Pat. Nos.4,995,385 and 4,069,819). Other examples of inhalers include theSpinhalerg® (Fisons, Loughborough, U.K.), Rotahale® (Glaxo-Wellcome,Research Triangle Park, N.C.).

In comparison to “single-step” inhalers, existing “multi-step inhalers”are more complex to operate and tend to be more costly since extraenergy is needed to deliver a drug to the lungs. This energy increaseswith increasing drug mass. On the other hand, “high efficiency” of drugdelivery to the respiratory tract, meaning about 50% of the drug massinitially contained in a drug receptacle, (i.e., the “nominal dose”), istypically only achieved with breath-activated, multi-step inhalersystems. Therefore, patients have until now needed to make a choicebetween cost/complexity and efficiency of drug delivery. The reason forthis trade-off is that existing inhalation methodologies and devices areassociated with inherent formulation inefficiencies and/or inherentdevice design limitations. Such inefficiencies result in unwanted druglosses and elevated overall cost of treatment. In addition, and often asa consequence, existing inhalation devices and methodologies can oftenfail to deliver to the lung a sufficient (i.e., therapeutic) mass ofdrug in a single breath. Currently, the amount of drug that can bedelivered to the lung in a single breath, via liquid or dry powderinhalers generally does not exceed 5 mg (Cipolla, et al., Resp. DrugDelivery VII 2000:231-239 (2000)).

Therefore a need exists for delivering to the pulmonary system abioactive agent wherein at least about 50% of the nominal dose of thebioactive agent is delivered to the pulmonary system via a single stepinhalation system. A need also exists for delivery of a relatively largemass of a bioactive agent, such as, for example, a therapeutic,prophylactic or diagnostic agent. A need further exists for methods ofdelivering to the pulmonary system, in a single step, from a simplebreath-activated device, a single, high dose of a bioactive agent.

SUMMARY OF THE INVENTION

The invention is related to methods of delivery of a bioactive agent tothe pulmonary system.

In one embodiment of the invention, a method of delivering a therapeuticdose of a bioactive agent to the pulmonary system, in a single,breath-activated step, includes administering particles, from areceptacle having, holding, containing or enclosing a mass of particles,to the respiratory tract of a subject, wherein at least 50% of the massof particles is delivered. The particles have a tap density of less thanabout 0.4 g/cm³. In another embodiment of the invention, a method ofdelivering a therapeutic dose of a bioactive agent to the pulmonarysystem in a single breath, includes administering particles from areceptacle. The particles have a tap density of at least about 0.4 g/cm³and deliver to the pulmonary system at least about 5 milligrams,preferably at least about 10 milligrams of a bioactive agent. In apreferred embodiment, the particles deliver at least about 15 milligramsof bioactive agent. In another preferred embodiment, the particlesdeliver at least about 20 milligrams of bioactive agent. In stillanother preferred embodiment, the particles deliver at least about 25milligrams of bioactive agent. In a further preferred embodiment, theparticles deliver at least about 30 milligrams of bioactive agent inwhich the receptacle has a volume of at least 0.48 cm³. Higher amountscan also be delivered, for example the particles can deliver at leastabout 35, 40 or 50 milligrams of bioactive agent. In other embodiments,the receptacle can have a volume of 0.95 cm^(3.)

In one embodiment the receptacle has a volume of at least about 0.37cm³and can have a design suitable for use in a dry powder inhaler. Largerreceptacles having a volume of at least about 0.48 cm³, 0.67 cm³ or 0.95cm³ also can be employed.

In a preferred embodiment, the energy holding the particles of the drypowder in an aggregated state is such that a patient's breath, over areasonable physiological range of inhalation flow rates is sufficient todeaggregate the powder contained in the receptacle into respirableparticles. The deaggregated particles can penetrate via the patient'sbreath into and deposit in the airways and/or deep lung with highefficiency.

In one embodiment of the invention, the particles have a tap density ofless than about 0.4 g/cm³, preferably around 0.1 g/cm³ or less. Inanother embodiment, the particles have a mass median geometric diameter(MMGD) larger than 5 μm, preferably around about 10 μm or larger. In yetanother embodiment, the particles have a mass median aerodynamicdiameter (MMAD) ranging from about 1 μm to about 5 μm.

The invention has numerous advantages. For example, a large single doseof a therapeutic, prophylactic or diagnostic agent can be administeredto the pulmonary system via a DPI with high efficiency. The inventionemploys a simple, cost effective device for pulmonary delivery whichincreases efficiency and minimizes wasted drug. Since dosage frequencycan be reduced by the delivery method of the invention, patientcompliance to treatment or prophylaxis protocols is expected to improve.Pulmonary delivery advantageously can eliminate the need for injection.For example, the requirement for daily insulin injections can beavoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing mass median geometric diameter (MMGD) inmicrons plotted against pressure for micronized albuterol sulfate(diamonds), spray dried albuterol sulfate (squares) and spray dried hGH(triangles).

FIG. 2A is a bar graph showing median geometric diameter of micronizedalbuterol sulfate, spray dried albuterol sulfate and spray dried hGH asprimary particles (left bar of each pair), as measured by RODOS,compared to emitted particles (right bar of each pair) out of theinhaler at 30 L/min, as measured by IHA.

FIG. 2B is a bar graph showing median aerodynamic diameter of micronizedalbuterol sulfate and spray dried albuterol sulfate as primary particles(left bar), as measured by a AeroDispenser, compared to emittedparticles (right bar) out of the inhaler at 30 L/min, as measured byAeroBreather.

FIG. 3 is a bar graph showing the Fine Particle Fraction (FPF)>4.0microns of the Emitted Dose Using DPI's at 60 L/min.

FIG. 4 is a bar graph showing a comparison of mass (left bar) and gammacount (right bar) particle size distributions of radio labeledparticles.

FIG. 5 is a graph showing the mass deposited in the lungs relative tothe nominal dose (diamonds). The average deposition for the 10individuals was 59% (dotted line).

FIG. 6 is a bar graph showing a comparison of mass fractiondistributions obtained for 6 (left bar) and 50 mg (right bar) fillweights.

FIG. 7 is a graph showing the relative lung deposition of particles ofthe instant invention (circles) over a range of inspiratory flow ratesin healthy volunteers. This is compared to lung deposition from drypowder inhalers (DPI's) (solid line) over the same range of inspiratoryflow rates. For comparison to DPI's, deposition efficiency of theparticles of the present invention were normalized to an average valueof 1.0 (dotted line). The average efficiency of mass deposited in thelung divided by the nominal dose for particles of present invention is59% as represented in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

The features and other details of the invention, either as steps of theinvention or as combination of parts of the invention, will now be moreparticularly described with reference to the accompanying drawings andpointed out in the claims. It will be understood that the particularembodiments of the invention are shown by way of illustration and not aslimitations of the invention. The principle feature of this inventionmay be employed in various embodiments without departing from the scopeof the invention.

The invention is related to methods of delivery to the pulmonary systemof a subject particles comprising a bioactive agent.

The methods of the invention relate to administering to the respiratorytract of a subject particles enclosed in a receptacle. As used herein,the term “receptacle” includes but is not limited to, for example, acapsule, blister, film covered container well, chamber and othersuitable means of storing a powder in an inhalation device known tothose skilled in the art.

In a preferred embodiment, the receptacle is used in a dry powderinhaler. Examples of dry powder inhalers that can be employed in themethods of the invention include but are not limited to the inhalersdisclosed is U.S. Pat. Nos. 4,995,385 and 4,069,819, the Spinhaler®(Fisons, Loughborough, U.K,), Rotahaler® (Glaxo-Welcome ResearchTriangle Technology Park, North Carolina), FlowCaps® (Hovione, Loures,Portugal), Inhalator® (Boehringer-Ingelheim, Germany), and theAerolizer® (Novartis, Switzerland), the Diskhaler (Glaxo-Wellcome, RTP,NC) and others known to those skilled in the art.

In one embodiment, the volume of the receptacle is at least about 0.37cm³. In another embodiment, the volume of the receptacle is at leastabout 0.48 cm³. In yet another embodiment, are receptacles having avolume of at least about 0.67 cm³ or 0.95 cm³. In one embodiment of theinvention, the receptacle is a capsule designated with a capsule size 2,1, 0, 00 or 000. Suitable capsules can be obtained, for example, fromShionogi (Rockville, Md.). Blisters can be obtained, for example, fromHueck Foils, (Wall, N.J.)

The receptacle encloses or stores particles, also referred to herein aspowders. The receptacle is filled with particles, as known in the art.For example, vacuum filling or tamping technologies may be used.Generally, filling the receptacle with powder can be carried out bymethods known in the art. In one embodiment of the invention, theparticle or powder enclosed or stored in the receptacle have a mass ofat least about 5 milligrams. Preferably, the mass of the particlesstored or enclosed in the receptacle is at least about 10 milligrams.

Particles, especially highly dispersible particles as defined herein,stored in the receptacle comprise a bioactive agent. Examples ofbioactive agents include therapeutic, prophylactic or diagnostic agents.Specific examples of bioactive agents include drugs, pharmaceuticalformulations, vitamins, pharmaceutical adjuvants, proteins, peptides,polypeptides, hormones, amino acids, nucleic acids, vaccineformulations, inactivated viruses, lung surfactants and any combinationsthereof. Other examples include synthetic inorganic and organiccompounds, proteins and peptides, polysaccharides and other sugars,lipids, and DNA and RNA nucleic acid sequences having therapeutic,prophylactic or diagnostic activities. Nucleic acid sequences includegenes, antisense molecules which bind to complementary DNA to inhibittranscription, and ribozymes. The agents to be incorporated can have avariety of biological activities, such as vasoactive agents, neuroactiveagents, hormones, anticoagulants, immunomodulating agents, cytotoxicagents, prophylactic agents, antibiotics, antivirals, antisense,antigens, and antibodies, such as, for example, monoclonal antibodies,e.g., palivizumab (Medimmune, Gaithersberg, Md.). In some instances, theproteins may be antibodies or antigens which otherwise would have to beadministered by injection to elicit an appropriate response. Compoundswith a wide range of molecular weight can be encapsulated, for example,between 100 and 500,000 Daltons. Proteins are defmed as consisting of100 amino acid residues or more; peptides are less than 100 amino acidresidues. Unless otherwise stated, the term protein refers to bothproteins and peptides. Examples include insulin and other hormones.Polysaccharides, such as heparin, can also be adninistered.

The particles, especially the highly dispersible particles describedherein, may include a therapeutic or prophylactic agent suitable forsystemic treatment. Alternatively, the particles can include atherapeutic or prophylactic agent for local delivery within the lung,such as, for example, agents for the treatment of asthma, emphysema, orcystic fibrosis, or for systemic treatment. For example, genes for thetreatment of diseases such as cystic fibrosis can be administered, ascan beta agonists for asthma. Other specific therapeutic agents include,but are not limited to, human growth hormone, interleukins, insulin,calcitonin, leutinizing hormone releasing hormone gonadotropin-releasinghormone (“LHRH”) and analogs thereof (e.g. leoprolide), granulocytecolony-stimulating factor (“G-CSF”), parathyroid hormone-relatedpeptide, somatostatin, testosterone, progesterone, estradiol, nicotine,fentanyl, norethisterone, clonidine, scopolomine, salicylate, cromolynsodium, salmeterol, formeterol, ipratropium bromide, albuterol,fluticasone and valium. Other suitable therapeutic or prophylatic agentsinclude, but are not limited to those listed in U.S. Pat. No. 5,875,776,the entire teachings of which are incorporated herein by reference.Those therapeutic agents which are charged, such as most of theproteins, including insulin, can be administered as a complex betweenthe charged therapeutic agent and a molecule of opposite charge.Preferably, the molecule of opposite charge is a charged lipid or anoppositely charged protein. The particles can incorporate substancessuch as lipids which allow for the sustained release of small and largemolecules. Addition of these complexes or substances is applicable toparticles of any size and shape, and is especially useful for alteringthe rate of release of therapeutic agents from inhaled particles.

Any of a variety of diagnostic agents can be incorporated within thehighly dispersible particles, which can locally or systemically deliverthe incorporated agents following administration to a patient. Particlesincorporating diagnostic agents can be detected using standardtechniques available in the art and commercially available equipment.

Any biocompatible or pharmacologically acceptable gas, for example, canbe incorporated into the particles or trapped in the pores of theparticles using technology known to those skilled in the art. The termgas refers to any compound which is a gas or capable of forming a gas atthe temperature at which imaging is being performed. In one embodiment,retention of gas in the particles is improved by forming agas-impermeable barrier around the particles. Such barriers are wellknown to those of skill in the art.

Other imaging agents which may be utilized include commerciallyavailable agents used in positron emission tomography (PET), computerassisted tomography (CAT), single photon emission computerizedtomography, x-ray, fluoroscopy, and magnetic resonance imaging (MRI).

Examples of suitable materials for use as contrast agents in MRI includethe gadolinium chelates currently available, such as diethylene triaminepentacetic acid (DTPA) and gadopentotate dimeglumine, as well as iron,magnesium, manganese, copper and chromium.

Examples of materials useful for CAT and x-rays include iodine basedmaterials for intravenous administration, such as ionic monomerstypified by diatrizoate and iothalamate, non-ionic monomers such asiopamidol, isohexol, and ioversol, non-ionic dimers, such as iotrol andiodixanol, and ionic dimers, for example, ioxagalte.

Bioactive agents also include targeting molecules which can be attachedto the particles via reactive functional groups on the particles. Forexample, targeting molecules can be attached to the amino acid groups offunctionalized polyester graft copolymer particles, such as poly(lacticacid-co-lysine) (PLAL-Lys) particles. Targeting molecules permit bindinginteraction of the particle with specific receptor sites, such as thosewithin the lungs. The particles can be targeted by attachment of ligandswhich specifically or non-specifically bind to particular targets.Exemplary targeting molecules include antibodies and fragments thereofincluding the variable regions, lectins, and hormones or other organicmolecules capable of specific binding, for example, to receptors on thesurfaces of the target cells.

Bioactive agents can also include surfactants such as surfactantsendogenous to the lung; both naturally occurring and synthetic lungsurfactants are included.

In one embodiment of the invention, the receptacle encloses a mass ofparticles, especially a mass of highly dispersible particles describedherein. The mass of particles comprises a nominal dose of the bioactiveagent. As used herein, the phrase “nominal dose” means the total mass ofbioactive agent which is present in the mass of particles in thereceptacle and represents the maximum amount of bioactive agentavailable for administration in a single breath.

Particles stored or enclosed in the receptacles are administered to therespiratory tract of a subject. As used herein, the terms“administration” or “administering” of particles refer to introducingparticles to the respiratory tract of a subject (through the nose and/orthrough the mouth).

In one embodiment of the invention, the particles are administered in asingle, breath-activated step. As used herein, the phrases“breath-activated” and “breath-actuated” are used interchangeably. Asused herein, “a single, bieath-activated step” means that particles aredispersed and inhaled in one step. For example, in single,breath-activated inhalation devices, the energy of the subject'sinhalation both disperses particles and draws them into the oral ornasopharyngeal cavity. Suitable inhalers which are single,breath-actuated inhalers that can be employed in the methods of theinvention include but are not limited to simple, dry powder inhalersdisclosed in U.S. Pat. Nos. 4,995,385 and 4,069,819, the Spinhaler®(Fisons, Loughborough, U.K.), Rotahaler® (Glaxo-Wellcome, ResearchTriangle Technology Park, North Carolina), FlowCaps® (Hovione, Loures,Portugal), Inhalator® (Boehringer-Ingelheim, Germany), and theAerolizer® (Novartis, Switzerland), the Diskhaler (Glaxo-Wellcome, RTP,NC) and others, such as known to those skilled in the art. “Singlebreath” administration can include single, breath-activatedadministration, but also administration during which the particles orpowders are first dispersed, followed by the inhalation or inspirationof the dispersed particles. In the latter mode of administration,additional energy than the energy supplied by the subject's inhalationdisperses the particles. An example of a single breath inhaler whichemploys energy other than the energy generated by the patient'sinhalation includes but is not limited to the device described in U.S.Pat. No. 5,997,848 issued to Patton et al. on Dec. 7, 1999, the entireteachings of which are incorporated herein by reference.

In a preferred embodiment, the receptacle enclosing the particles isemptied in a single, breath-activated step. In another preferredembodiment, the receptacle enclosing the particles is emptied in asingle inhalation. As used herein, the term “emptied” means that atleast 50% of the particle mass enclosed in the receptacle is emittedfrom the inhaler during administration of the particles to a subject'srespiratory system.

In a preferred embodiment of the invention, the particles administeredare highly dispersible. As used herein, the phrase “highly dispersible”particles or powders refers to particles or powders which can bedispersed by a RODOS dry powder disperser (or equivalent technique) suchthat at about 1 Bar, particles of the dry powder emit from the RODOSorifice with geometric diameters, as measured by a HELOS or other laserdiffraction system, that are less than about 1.5 times the geometricparticle size as measured at 4 Bar. Highly dispersible powders have alow tendency to agglomerate, aggregate or clump together and/or, ifagglomerated, aggregated or clumped together, are easily dispersed orde-agglomerated as they emit from an inhaler and are breathed in by thesubject. Typically, the highly dispersible particles suitable in themethods of the invention display very low aggregation compared tostandard micronized powders which have similar aerodynamic diameters andwhich are suitable for delivery to the pulmonary system. Properties thatenhance dispersibility include, for example, particle charge, surfaceroughness, surface chemistry and relatively large geometric diameters.In one embodiment, because the attractive forces between particles of apowder varies (for constant powder mass) inversely with the square ofthe geometric diameter and the shear force seen by a particle increaseswith the square of the geometric diameter, the ease of dispersibility ofa powder is on the order of the inverse of the geometric diameter raisedto the fourth power. The increased particle size diminishesinterparticle adhesion forces. (Visser, J., Powder Technology, 58: 1-10(1989)). Thus, large particle size, all other things equivalent,increases efficiency of aerosolization to the lungs for particles of lowenvelope mass density. Increased surface irregularities, and roughnessalso can enhance particle dispersibility. Surface roughness can beexpressed, for example by rugosity.

The particles preferably are biodegradable and biocompatible, andoptionally are capable of biodegrading at a controlled rate for deliveryof a therapeutic, prophylactic, or diagnostic agent. In addition to thebioactive agent, the particles can further include a variety ofmaterials. Both inorganic and organic materials can be used. Forexample, ceramics may be used. Polymeric as well as non-polymericmaterials, such as fatty acids, may be used to form aerodynamicallylight particles. Other suitable materials include, but are not limitedto, amino acids, gelatin, polyethylene glycol, trehalose, lactose, anddextran. Preferred particle compositions are further described below.

In one embodiment of the invention, particles administered to asubject's respiratory tract have a tap density of less than about 0.4g/cm³. Particles having a tap density of less than about 0.4 g/cm³ arereferred to herein as “aerodynamically light”. In a preferredembodiment, the particles have a tap density of near to or less thanabout 0.1 g/cm³. Tap density is a measure of the envelope mass densitycharacterizing a particle. The envelope mass density of a particle of astatistically isotropic shape is defined as the mass of the particledivided by the minimum sphere envelope volume within which it can beenclosed. Features which can contribute to low tap density includeirregular surface texture and hollow or porous structure.

Tap density can be measured by using instruments known to those skilledin the art such as the Dual Platformn Microprocessor Controlled TapDensity Tester (Vankel, N.C.). Tap density is a standard measure of theenvelope mass density. Tap density can be determined using the method ofUSP Bulk Density and Tapped Density, United States Pharmacopiaconvention, Rockville, Md., 10_(th) Supplement, 4950-4951, 1999.

In another embodiment, the particles have a mass median geometricdiameter (MMGD) greater than about 5 μm and preferably near to orgreater than about 10 μm. In one embodiment, the particles have a MMGDgreater than about 5 μm and ranging to about 30 μm. In anotherembodiment, the particles have a MMGD ranging from about 10 μm to about30 μm.

The mass MMGD of the particles can be measured using an electrical zonesensing instrument such as Coulter Multisizer lIe (Coulter Electronics,Luton, Beds, England) or a laser diffraction instrument (for exampleHelos, Sympatec, Inc., Princeton, N.J.). The diameter of particles in asample will range depending upon factors such as particle compositionand methods of synthesis. The distribution of size of particles in asample can be selected to permit optimal deposition within targetedsites within the respiratory tract.

The aerodynamically light particles suitable for use in the instantinvention may be fabricated or separated, for example by filtration orcentrifugation, to provide a particle sample with a preselected sizedistribution. For example, greater than 30%, 50%, 70%, or 80% of theparticles in a sample can have a diameter within a selected range of atleast 5 μm. The selected range within which a certain percentage of theparticles must fall may be for example, between about 5 and 30 μm, oroptionally between 5 and 15 μm. In one preferred embodiment, at least aportion of the particles have a diameter between about 9 and 11 μm.Optionally, the particle sample also can be fabricated wherein at least90%, or optionally 95% or 99%, have a diameter within the selectedrange. The presence of the higher proportion of the aerodynamicallylight, larger diameter (at least about 5 μm) particles in the particlesample enhances the delivery of therapeutic prophylactic, or diagnosticagents incorporated therein to the deep lung.

In one embodiment, in the particle sample, the interquartile range maybe 2 μm, with a mean diameter for example, between about 7.5 and 13.5μm. Thus, for example, between at least 30% and 40% of the particles mayhave diameters within the selected range. Preferably, the saidpercentages of particles have diameters within a 1 μm range, forexample, between 6.0 and 7.0 μm, 10.0 and 11.0 μm or 13.0 and 14.0 μm.

In a further embodiment, the particles have an aerodynamic diameterranging from about 1 μm to about 5 μm. The aerodynamic diameter,d_(aer), can be calculated from the equation:d _(aer) =d _(g)√ρ_(tap)where d_(g) is the geometric diameter, for example the MMGD and ρ is thepowder density. Experimentally, aerodynamic diameter can be determinedby employing a gravitational settling method, whereby the time for anensemble of particles to settle a certain distance is used to inferdirectly the aerodynamic diameter of the particles. An indirect methodfor measuring the mass median aerodynamic diameter (MMAD) is themulti-stage liquid impinger (MSLI).

In one embodiment of the invention, at least 50% of the mass of theparticles stored in the receptacle are delivered to a subject'srespiratory tract in a single, breath-activated step. Preferably, atleast 55% of the mass of particles is delivered.

In another embodiment of the invention, at least 5 milligrams andpreferably at least 10 milligrams of bioactive agent is delivered byadministering, in a single breath, to a subject's respiratory tractparticles enclosed in the receptacle. Amounts of at least 15, preferablyof at least 20 and more preferably of at least 25, 30, 35, 40 and 50milligrams can be delivered. In a preferred embodiment, amounts of atleast 35 milligrams are delivered. In another preferred embodiment,amounts of at least 50 milligrams are delivered.

Particles administered to the respiratory tract of the subject aredelivered to the pulmonary system. Particles suitable for use in themethods of the invention can travel through the upper airways(oropharynx and larynx), the lower airways which include the tracheafollowed by bifircations into the bronchi and bronchioli and through theterminal bronchioli which in turn divide into respiratory bronchiolileading then to the ultimate respiratory zone, the alveoli or the deeplung. In one embodiment of the invention, most of the mass of particlesdeposit in the deep lung. In another embodiment of the invention,delivery is primarily to the central airways. In other embodiments,delivery is to the upper airways.

The particles suitable for use in the instant invention may befabricated with the appropriate material, surface roughness, diameterand tap density for localized delivery to selected regions of therespiratory tract such as the deep lung, central or upper airways. Forexample, higher density or larger particles may be used for upper airwaydelivery, or a mixture of different sized particles in a sample,provided with the same or different therapeutic agent may beadministered to target different regions of the lung in oneadministration. Particles with degradation and release times rangingfrom seconds to months can be designed and fabricated, based on factorssuch as the particle material.

Delivery to the pulmonary system of particles in a single,breath-actuated step is enhanced by employing particles which aredispersed at relatively low energies, such as, for example, at energiestypically supplied by a subject's inhalation. Such energies are referredto herein as “low”. As used herein, “low energy administration” refersto administration wherein the energy applied to disperse and inhale theparticles is in the range typically supplied by a subject duringinhaling.

In one embodiment of the invention, highly dispersible particlesadministered comprise a bioactive agent and a biocompatible, andpreferably biodegradable polymer, copolymer, or blend. The polymers maybe tailored to optimize different characteristics of the particleincluding: i) interactions between the agent to be delivered and thepolymer to provide stabilization of the agent and retention of activityupon delivery; ii) rate of polymer degradation and, thereby, rate ofdrug release profiles; iii) surface characteristics and targetingcapabilities via chemical modification; and iv) particle porosity.

Surface eroding polymers such as polyanhydrides may be used to form theparticles. For example, polyanhydrides such aspoly[(p-carboxyphenoxy)hexane anhydride] (PCPH) may be used.Biodegradable polyanhydrides are described in U.S. Pat. No. 4,857,311.Bulk eroding polymers such as those based on polyesters includingpoly(hydroxy acids) also can be used. For example, polyglycolic acid(PGA), polylactic acid (PLA), or copolymers thereof may be used to formthe particles. The polyester may also have a charged or functionalizablegroup, such as an amino acid. In a preferred embodiment, particles withcontrolled release properties can be formed of poly(D,L-lactic acid)and/or poly(DL-lactic-co-glycolic acid) (“PLGA”) which incorporate asurfactant such as dipalmitoyl phosphatidylcholine (DPPC).

Other polymers include polyamides, polycarbonates, polyalkylenes such aspolyethylene, polypropylene, poly(ethylene glycol), poly(ethyleneoxide), poly(ethylene terephthalate), poly vinyl compounds such aspolyvinyl alcohols, polyvinyl ethers, and polyvinyl esters, polymers ofacrylic and methacrylic acids, celluloses and other polysaccharides, andpeptides or proteins, or copolymers or blends thereof. Polymers may beselected with or modified to have the appropriate stability anddegradation rates in vivo for different controlled drug deliveryapplications.

Highly dispersible particles can be formed from functionalized polyestergraft copolymers, as described in Hrkach et al., Macromolecules, 28:4736-4739 (1995); and Hrkach et al., “Poly(L-Lactic acid-co-amino acid)Graft Copolymers: A Class of Functional Biodegradable Biomaterials” inHydrogels and Biodegradable Polymers for Bioapplications, ACS SymposiurnSeries No. 627, Raphael M. Ottenbrite et al., Eds., American ChemicalSociety, Chapter 8, pp. 93-101, 1996.

In a preferred embodiment of the invention, highly dispersible particlesincluding a bioactive agent and a phospholipid are administered.Examples of suitable phospholipids include, among others,phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols,phosphatidylserines, phosphatidylinositols and combinations thereof.Specific examples of phospholipids include but are not limited tophosphatidylcholines dipalmitoyl phosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE), distearoyl phosphatidyicholine (DSPC),dipalmitoyl phosphatidyl glycerol (DPPG) or any combination thereof.Other phospholipids are known to those skilled in the art. In apreferred embodiment, the phospholipids are endogenous to the lung.

The phospholipid, can be present in the particles in an amount rangingfrom about 0 to about 90 weight %. More commonly it can be present inthe particles in an amount ranging from about 10 to about 60 weight %.

In another embodiment of the invention, the phospholipids orcombinations thereof are selected to impart controlled releaseproperties to the highly dispersible particles. The phase transitiontemperature of a specific phospholipid can be below, around or above thephysiological body temperature of a patient. Preferred phase transitiontemperatures range from 30° C. to 50° C., (e.g., within ±10 degrees ofthe normal body temperature of patient). By selecting phospholipids orcombinations of phospholipids according to their phase transitiontemperature, the particles can be tailored to have controlled releaseproperties. For example, by administering particles which include aphospholipid or combination of phospholipids which have a phasetransition temperature higher than the patient's body temperature, therelease of dopamine precursor, agonist or any combination of precursorsand/or agonists can be slowed down. On the other hand, rapid release canbe obtained by including in the particles phospholipids having lowertransition temperatures. Particles having controlled release propertiesand methods of modulating release of a biologically active agent aredescribed in U.S. Provisional Patent Application No. 60/150,742 entitledModulation of Release From Dry Powder Formulations by Controlling MatrixTransition, filed on Aug. 25, 1999, the contents of which areincorporated herein in their entirety.

In another embodiment of the invention the particles can include asurfactant. As used herein, the term “surfactant” refers to any agentwhich preferentially absorbs to an interface between two immisciblephases, such as the interface between water and an organic polymersolution, a water/air interface or organic solvent/air interface.Surfactants generally possess a hydrophilic moiety and a lipophilicmoiety, such that, upon absorbing to microparticles, they tend topresent moieties to the external environment that do not attractsimilarly-coated particles, thus reducing particle agglomeration.

In addition to lung surfactants, such as, for example, phospholipidsdiscussed above, suitable surfactants include but are not limited tohexadecanol; fatty alcohols such as polyethylene glycol (PEG);polyoxyethylene-9-lauryl ether; a surface active fatty acid, such aspalmitic acid or oleic acid; glycocholate; surfactin; a poloxomer; asorbitan fatty acid ester such as sorbitan trioleate (Span 85); andtyloxapol.

The surfactant can be present in the particles in an amount ranging fromabout 0 to about 90 weight %. Preferably, it can be present in theparticles in an amount ranging from about 10 to about 60 weight %.

Methods of preparing and administering particles which areaerodynamically light and include surfactants, and, in particularphospholipids, are disclosed in U.S. Pat. No. 5,855,913, issued on Jan.5, 1999 to Hanes et al. and in U.S. Pat. No. 5,985,309, issued on Nov.16, 1999 to Edwards et al. The teachings of both are incorporated hereinby reference in their entirety. Methods of administering particles topatients in acute distress are disclosed. The highly dispersibleparticles being administered in the instant invention are capable ofbeing delivered to the lung and absorbed into the system when otherconventional means of delivering drugs fail.

In yet another embodiment, highly dispersible particles only including abioactive agent and surfactant are administered. Highly dispersibleparticles may be formed of the surfactant and include a therapeuticprophylactic, or diagnostic agent, to improve aerosolization efficiencydue to reduced particle surface interactions, and to potentially reduceloss of the agent due to phagocytosis by alveolar macrophages.

In another embodiment of the invention, highly dispersible particlesincluding an amino acid are administered. Hydrophobic amino acids arepreferred. Suitable amino acids include naturally occurring andnon-naturally occurring hydrophobic amino acids. Some naturallyoccurring hydrophobic amino acids, including but not limited to,non-naturally occurring amino acids include, for example, beta-arninoacids. Both D, L and racemic configurations of hydrophobic amino acidscan be employed. Suitable hydrophobic amino acids can also include aminoacid analogs. As used herein, an amino acid analog includes the D or Lconfiguration of an amino acid having the following formula:—NH—CHR—CO—, wherein R is an aliphatic group, a substituted aliphaticgroup, a benzyl group, a substituted benzyl group, an aromatic group ora substituted aromatic group and wherein R does not correspond to theside chain of a naturally-occurring amino acid. As used herein,aliphatic groups include straight chained, branched or cyclic C1-C8hydrocarbons which are completely saturated, which contain one or twoheteroatoms such as nitrogen, oxygen or sulfur and/or which contain oneor more units of desaturation. Aromatic groups include carbocyclicaromatic groups such as phenyl and naphthyl and heterocyclic aromaticgroups such as imidazolyl, indolyl, thienyl, furanyl, pyridyl, pyranyl,oxazolyl, benzothienyl, benzofuranyl, quinolinyl, isoquinolinyl andacridintyl.

Suitable substituents on an aliphatic, aromatic or benzyl group include—OH, halogen (—Br,—Cl,—I and —F)—O(aliphatic, substituted aliphatic,benzyl, substituted benzyl, aryl or substituted aryl group),—CN, —NO₂,—COOH, —NH₂, —NH(aliphatic group, substituted aliphatic, benzyl,substituted benzyl, aryl or substituted aryl group), —N(aliphatic group,substituted aliphatic, benzyl, substituted benzyl, aryl or substitutedaryl group)₂, —COO(aliphatic group, substituted aliphatic, benzyl,substituted benzyl, aryl or substituted aryl group), —CONH₂,—CONH(aliphatic, substituted aliphatic group, benzyl, substitutedbenzyl, aryl or substituted aryl group)), —SH,—S(aliphatic, substitutedaliphatic, benzyl, substituted benzyl, aromatic or substituted aromaticgroup) and —NH—C(═NH)—NH₂. A substituted benzylic or aromatic group canalso have an aliphatic or substituted aliphatic group as a substituent.A substituted aliphatic group can also have a benzyl, substitutedbenzyl, aryl or substituted aryl group as a substituent. A substitutedaliphatic, substituted aromatic or substituted benzyl group can have oneor more substituents. Modifying an amino acid substituent can increase,for example, the lypophilicity or hydrophobicity of natural amino acidswhich are hydrophilic.

A number of the suitable amino acids, amino acids analogs and saltsthereof can obtained commercially. Others can be synthesized by methodsknown in the art. Synthetic techniques are described, for example, inGreen and Wuts, “Protecting Groups in Organic Synthesis”, John Wiley andSons, Chapters 5 and 7, 1991.

Hydrophobicity is generally defined with respect to the partition of anamino acid between a nonpolar solvent and water. Hydrophobic amino acidsare those acids which show a preference for the nonpolar solvent.Relative hydrophobicity of amino acids can be expressed on ahydrophobicity scale on which glycine has the value 0.5. On such ascale, amino acids which have a preference for water have values below0.5 and those that have a preference for nonpolar solvents have a valueabove 0.5. As used herein, the term hydrophobic amino acid refers to anamino acid that, on the hydrophobicity scale, has a value greater orequal to 0.5, in other words, has a tendency to partition in thenonpolar acid which is at least equal to that of glycine.

Examples of amino acids which can be employed include, but are notlimited to: glycine, proline, alanine, cysteine, methionine, valine,leucine, tyosine, isoleucine, phenylalanine, tryptophan. Preferredhydrophobic amino acids include leucine, isoleucine, alanine, valine,phenylalanine and glycine. Combinations of hydrophobic amino acids canalso be employed. Furthermore, combinations of hydrophobic andhydrophilic (preferentially partitioning in water) amino acids, wherethe overall combination is hydrophobic, can also be employed.

The amino acid can be present in the particles of the invention in anamount of at least 10 weight %. Preferably, the amino acid can bepresent in the particles in an amount ranging from about 20 to about 80weight %. The salt of a hydrophobic amino acid can be present in theparticles of the invention in an amount of at least 10 weight percent.Preferably, the amino acid salt is present in the particles in an amountranging from about 20 to about 80 weight %. In preferred embodiments theparticles have a tap density of less than about 0.4 g/cm^(3.)

Methods of forming and delivering particles which include an amino acidare described in U.S. patent application Ser. No 09/382,959, filed onAug. 25, 1999, entitled Use of Simple Amino Acids to Form PorousParticles During Spray Drying, the teachings of which are incorporatedherein by reference in their entirety.

The particles of the invention can also include excipients such as oneor more of the following; a sugar, such as lactose, a protein, such asalbumin, cholesterol and/or a surfactant.

If the agent to be delivered is negatively charged (such as insulin),protamine or other positively charged molecules can be added to providea lipophilic complex which results in the sustained release of thenegatively charged agent. Negatively charged molecules can be used torender insoluble positively charged agents.

Highly dispersible particles suitable for use in the methods of theinvention may be prepared using single and double emulsion solventevaporation, spray drying, solvent extraction, solvent evaporation,phase separation, simple and complex coacervation, interfacialpolymerization, supercritical carbon dioxide (CO₂) and other methodswell known to those of ordinary skill in the art. Particles may be madeusing methods for making microspheres or microcapsules known in the art,provided that the conditions are optimized for forming particles withthe desired aerodynamic diameter, or additional steps are performed toselect particles with the density and diameter sufficient to provide theparticles with an aerodynamic diameter between one and five microns,preferably between one and three microns.

With some polymeric systems, polymeric particles prepared using a singleor double emulsion technique vary in size depending on the size of thedroplets. If droplets in water-in-oil emulsions are not of a suitablysmall size to form particles with the desired size range, smallerdroplets can be prepared, for example, by sonication or homogenizationof the emulsion, or by the addition of surfactants.

If the particles prepared by any of the above methods have a size rangeoutside of the desired range, particles can be sized, for example, usinga sieve, and further separated according to density using techniquesknown to those of skill in the art.

The particles are preferably prepared by spray drying.

The following equipment and reagents are referred to herein and forconvenience will be listed once with the pertinent information. Unlessotherwise indicated, all equipment was used as directed in themanufacturer's instructions. Also, unless otherwise indicated, othersimilar equipment can be used as well know to those skilled in the art.

Unless otherwise indicated, all equipment and reagents were used asdirected in the manufacturer's instructions. Further, unless otherwiseindicated, that suitable substitution for said equipment and reagentswould be available and well know to those skilled in the art.

-   (1) RODOS dry powder disperser (Sympatec Inc., Princeton, N.J.)-   (2) HELOS laser diffractometer (Sympatec Inc., N.J.)-   (3) Single-stage Andersen impactor (Andersen Inst., Sunyma, Ga.)-   (4) AeroDisperser (TSI, Inc., Amherst, Mass.)-   (5) Aerosizer (TSI Inc., Amherst, Mass.)-   (6) blister pack machine, Fantasy Blister Machine (Schaefer Tech,    Inc., Indianapolis, Ind.)-   (7) collapsed Andersen cascade impactor (consisting of stage 0 as    defined by manufacturer) and the filter stage (Anderson Inst.,    Sunyra, Ga.)-   (8) a spirometer (Spirometrics, USA, Auburn, Me.)-   (9) a multistage liquid impinger (MSLI) (Erweka, USA, Milford,    Conn.)-   (10) fluorescent spectroscope (Hitachi Instruments, San Jose,    Calif.)-   (11) gamma camera (generic)    Reagents-   albuterol sulfate particles (Profarrnco Inc., Italy)-   human growth hormone (Eli Lilly, Indianapolis, Ind.)-   size #2 methyl cellulose capsules (Shionogi, Japan)-   blister packs (Heuck Foils, Well, N.J.)-   DPPC (Avanti, Alabaster, Ala.)

As discussed in more detail in the Example section below, the methods ofthe instant invention require powders which exhibit good aerosolizationproperties from a simple inhaler device. In order to determine if apowder has the appropriate aerosolization properties, the powder istested for deaggregation and emission properties. Although those skilledin the art will recognize equivalent means to measure these properties,an example of an in vitro test which demonstrates delivery of a mass ofpowder onto an impactor is performed. The powder to be tested isintroduced into a powder dispensing apparatus, for example a RODOS drypowder disperser at varying shear forces. This is accomplished bymanipulating the regulator pressure of the air stream used to break upthe particles. The geometric size is measured to determine whether apowder has successfully deaggregated under the conditions. In additionto the deaggregation properties, it is possible to evaluate the abilityof a powder to emit from a simple, breath-activated inhaler. Examples ofinhalers suitable for the practice of the instant invention are theSpinhaler® (Fisons, Loughborough, U.K.), Rotahaler® (Glaxo-Wellcome,Research Triangle Park (RTP), North Carolina), FlowCaps® (Hovione,Loures, Portugal), Inhalator® Boehringer-lngelheim, Germany), and theAerolizer® (Novartis, Switzerland). It will be appreciated that otherinhalers such as the Diskhaler (Glaxo-Wellcome, RTP, N.C.) may also beused. Especially suitable inhalers are the simple, dry powder inhalers(U.S. Pat. Nos. 4,995,385 and 4,069,819). A specific non-limitingexample describing an experiment to determine the deaggregation andemission properties of three different powders is described in furtherdetail herein. Briefly, three different dry powders believed to havedifferent deaggregation properties were characterized. The first powderwas micronized albuterol sulfate particles. The second and third powderswere prepared by dissolving a combination of excipients and a bioactiveagent in an ethanol/water solvent system and spray drying to create drypowders. The geometric diameter, tap density and aerodynamic diameter ofthe three powders were determined.

The Applicants introduced the powders into and dispersed the powderthrough an orifice in the RODOS dry powder disperser at varying shearforces by manipulating the regulator pressure of the air stream used tobreak up the particles. The Applicants obtained the geometric sizedistribution from the HELOS laser diffractometer as the powder exitedand recorded the median value: The data was summarized and plotted asthe mass median geometric diameter (MMGD) against pressure.

Applicants postulated and through experimentation disclosed herein foundthat at high pressure, for example 3 or 4 bars, all three powders exitedthe disperser as primary (deaggregated) particles. This supports thefinding that relatively high energy successfully deaggregates all threepowders. However at pressures below 2 bars which more closelycorresponds with physiological breath rate, the micronized powder(Powder 1 Table 1) exited the orifice in an aggregated state, evidencedby a mean particle size leaving the orifice that was greater than thepowder's primary particle size. This is not the case for the spray driedpowders (Powder 2 and 3 Table 1), which emitted from the orifice atapproximately their primary particles size. These powders are highlydispersible powders.

Still further to evaluate the ability of the three powders to emit froma simple, breath-activated inhaler, the Applicants placed 5 mg of eachpowder in a size #2 methyl cellulose capsule and inserted the capsuleinto a breath-activated inhaler. It will be appreciated by those skilledin the art that the receptacle into which the powders are placed willdepend on the type of inhaler selected. The results are discussed in theExamples below. Generally, applicants found that given the relativelylow energy supplied by the inhaler to break up the powder, themicronized albuterol sulfate powder were emitted from the inhaler asaggregates with geometric diameters greater than 30 microns, eventhought their primary particle size, as measured by RODOS was on theorder of 2 microns. On the other hand, the highly dispersible particlesof spray dried albuterol sulfate of hGH were emitted at particle sizesthat were very comparable to their primary particle size. The sameresults were obtained from measurements of the aerodynamic diameter,with spray dried particles emitting with very similar aerodynamicdiameter as compared to the primary particles. Using the methods of theinstant invention, one skilled in the art can achieve high-efficiencydelivery from a simple breath-activated device by loading it with powderthat is highly dispersible.

A further feature of the instant invention is the ability to emit largepercentages of a nominal dose at low energy not only from single dose,breath-actuated inhaler but also from a range of breath-actuated DryPowder Inhalers (DPIs).

To illustrate that a highly dispersible powder can efficiently emit andpenetrate into the lungs from a range of breath-activated DPIS, theApplicants prepared a spray-dried powder comprised of sodium citrate,DPPC, calcium chloride buffer, and a rhodamine fluorescent label. Thisis explained thoroughly in Example 2. The powder possessed a medianaerodynamic diameter of 2.1 μm (measured by the AeroDisperser andAerosizer) and a geometric diameter of 11.0 μm (measured using theRODOS/HELOS combination described above). Applicants found that thepowders tested displayed excellent deaggregation properties.

In particular, the Applicants placed 5 mg of the powders to be tested inthe capsules using a semi-automated capsule filling device in thefollowing inhalers: a breath activated inhaler under development by theapplicant, the Spinhaler® (Fisons, Loughborough, U.K.), Rotahaler®(Glaxo-Wellcome, RTP, NC), FlowCaps® (Hovione, Loures, Portugal),Inhalator® (Boehringer-Ingelheim, Germany), and the Aerolizer®(Novartis, Switzerland). We also tested the Diskhaler (Glaxo-Wellcome,RTP, NC), for which 3 mg of the powder was machine-filled into theblister packs. Applicants connected each inhaler to a collapsed Andersencascade impactor (consisting of stage 0 and the filter stage,) andextracted air at 60 L/minute for 2 seconds after actuating the device.The fine particle fraction less than stage 0, having a 4.0 μm cut-off,was determined using fluorescent spectroscopy.

Applicants found that in each case, approximately 50% or more of theemitted dose displays a mean aerodynamic diameter (Da) less than 4 μm insize, indicating that the powder will efficiently enter the lungs of ahuman subject at a physiological breath rate, despite the simplicity ofthese breath-activated devices.

In order to test the highly dispersible powders in vivo, Applicantsperformed human deposition studies as described in Example 3 todetermine whether a highly dispersible powder emitted from a simplebreath-actuated inhaler could produce highly efficient delivery to thelungs (>50% of the nominal dose). This is especially important becausemany devices rely on inhalation by the patient to provide the power tobreak up the dry material int a free-flowing powder. Such devices proveineffective for those lacking the capacity to strongly inhale, such asyoung patients, old patients, infirm patients, or patients with asthmaor other breathing difficulties. An advantage of the method of theinstant invention is that highly efficient delivery can be achievedindependent of the flow rate. Thus, using the methods of the invention,even a weak inhalation is sufficient to delivery the desired dose. Thisis surprising in light of the expected capabilities of standard DPIs. Ascan be seen in FIG. 7 using the methods herein superior deliverycompared to standard DPIs can be achieved at flow rates ranging fromabout 25 L/min to about 75 L/min. The methods of the instant inventioncan be optimized at flow rates of at least about 20 L/min to about 90L/min. Powder possessing the following characteristics Dg=6.7 μm; p=0.06g/cc; Da=1.6 μm was labeled with ^(99m)Tc nanoparticles. Equivalencebetween the mass and gamma radiation particle size distributions wasobtained and is discussed in detail in Example 3 below. Approximately 5mg of powder was loaded into size 2 capsules. The capsules were placedinto a breath activated inhaler and actuated. Ten healthy subjectsinhaled through the inhaler at an approximately inspiratory flow rate of60 L/min. as measured by a spirometer. The deposition image was obtainedusing a gamma camera. The percentage lung deposition (relative to thenominal dose) obtained from the ten subjects is shown in FIG. 5. Theaverage lung deposition relative to the nominal dose was 59.0%. Thoseskilled in the art would recognize that such deposition levels confirmthat highly dispersible drug powder can be inhaled into the lungs withhigh efficiency using a single breath-actuated inhaler.

Still further, Applicants have discovered that the same preparations ofa highly dispersible powder that had excellent aerosolization from asingle inhaler can be used to deliver a surprisingly high dose in singleinhalation. The highly dispersible powder can be loaded into a largepre-metered dose (50 mg) and a smaller pre-metered dose (6 mg). Theparticle characteristics of the powder were as follows: Dg=10.6 μm;p=0.11 g/cc; Da=3.5 μm. One skilled in the art would appreciate thepossible ranges of characteristics of particles suitable for use in theinstant invention as disclosed previously herein.

The aerodynamic particle size distributions were characterized using amultistage liquid impinger (MSLI) [ ] operated at 60 L/min. Size 2capsules were used for the 6 mg dose and size 000 capsules were used forthe 50 mg dose. The Applicants compared the two particle sizedistributions obtained for the 6 and 50 mg doses. The fine particlefraction <6.8 μm relative to the total dose (FPF_(TD)<6.8 μm) for the 6and 50 mg doses were 74.4% and 75.0%, respectively. Thus Applicants havedemonstrated that a large dose of drug can be delivered to the lungswith equal efficiency as a small drug dose by combining the propertiesof a highly dispersible powder.

Exemplification

Unless otherwise noted, the apparatus and reagents used have beenobtained from the sources previously listed herein.

Example 1

The powders suitable for use in the methods of the instant invention arerequired to possess properties which exhibit good aerosolization from asimple inhaler device. To determine the properties, Applicantscharacterized three different dry powders believed to have differentdeaggregation properties. The first powder to be tested was micronizedalbuterol sulfate particles obtained from Spectrum Labs. The second and.third powders were prepared by spray-drying by dissolving a combinationof excipients and a bioactive agent in an ethanol/water solvent system.

Preparation of Microparticles

Placebo particle composition is 70/20/10% DPPC/sodium citrate/Calciumchloride 0.2 grams sodium citrate and 0.1 grams calcium chloride weredissolved in 0.1 1 liters water. A DPPC solution in ethanol was preparedby dissolving 0.7 g DPPC (DL-α-phosphatidylcholine dipalmitoyl, AvantiPolar Lipids, Alabaster, Ala.) in 0.89 liters of 95% ethanol. The sodiumcitrate/calcium chloride solution and the DPPC/ethanol solution werethen mixed together. The final total solute concentration is 1.0 g/Lmade up of 0.70 g/L DPPC, 0.2 g/L sodium citrate and 0.1 g/L calciumchloride in 85% ethanol/15% water.

hGH particle composition is: 58/38.5/3.5 hGH/DPPC/Sodium Phosphate 1.16gr hGH (Lilly, Indianapolis, Ind.) was dissolved in 300 ml sodiumphosphate buffer (10 mM, Ph 7.4). 0.77 g DPPC was dissolved in 700 mlethanol. The two solutions were then combined resulting in a finalsolute concentration of 2 g/L in 70/30 EtOH/H₂O.

Albuterol sulfate particle composition is 76/20/4 DSPC/Leucine/AlbuterolSulfate 2.28 g DSPC (disteoroyl phosphatidylcholine, Avanti Polar Labs)and 0.6 g Leucine (Spectrum Labs, Laguna Hills, Calif.) were dissolvedin 700 ml. ethanol. 0.12 g albuterol sulfate (Profarmco, Italy) wasdissolved in 300 ml water and then the two solutions were combined toyield a final solute concentration of 3 g/L in 70/30 EtOH/H₂O.

Spray Drying

A Niro Atomizer Portable Spray Dryer (Niro, Inc., Columbus, Md.) wasused to produce the dry powders. Compressed air with variable pressure(1 to 5 bar) ran a rotary atomizer (2,000 to 30,000 rpm) located abovethe dryer. Liquid feed with varying rate (20 to 66 ml/min) was pumpedcontinuously by an electronic metering pump (LMI, model #A151-192s) tothe atomizer. Both the inlet and outlet temperatures were measured. Theinlet temperature was controlled manually; it could be varied between100° C. and 400° C. and was established at 100, 110, 150, 175, or 200°C., with a limit of control of 5° C. The outlet temperature wasdetermined by the inlet temperature and such factors as the gas andliquid feed rates: it varied between 50° C. and 130° C. A container wastightly attached to the cyclone for collecting the powder product.

Results

The geometric diameter and tap density of the three powders are shown inTable 1.

TABLE 1 Powder Dg (μm) ρ(g/cc) Micronized Alb. Sulfate (1) 2.5 0.26Spray-Dried Alb. Sulfate (2) 8.0 0.20 Spray-Dried hGH (3) 14.5 0.07

To evaluate the deagglomeration properties of the three powders,Applicants introduced the powders into the RODOS dry powder disperser atvarying shear forces by manipulating the regulator pressure of the airstream used to break up the particles. Subsequently, following themanufacturer's instructions, Applicants obtained the geometric sizedistribution from the HELOS laser diffractometer and recorded the medianvalue. The data was summarized and plotted as volume median geometricdiameter (MMGD) against pressure.

FIG. 1 shows the results of this experiment. Applicants havedemonstrated that at high pressure, about greater than 2 bars andespecially about 3 to 4 bars, all three powders exit the disperser asprimary (deaggregated) particles. This supports the finding that arelatively high energy successfully deaggregates all three powders.However at pressures below 2 bars, the micronized powder [Powder 1]exited the orifice in an aggregated state. Evidence of this can be seenby a mean particle size leaving the orifice that was greater than thepowder's primary particle size. This was not the case for the spraydried powders [Powders 2 and 3], which emitted from the orifice atapproximately their primary particles' size. Powders 2 and 3 were highlydispersible powders.

Particles of the present invention were further characterized by thefollowing techniques. The primary geometric diameter was measured usinga RODOS dry powder disperser (Sympatec, Princeton, N.J.) in conjunctionwith a HELOS laser diffractometer (Sympatec). Powder was introduced intothe RODOS inlet and aerosolized by shear forces generated by acompressed air stream regulated at 4 bar. The aerosol cloud wassubsequently drawn into the measuring zone of the HELOS, where itscattered light from a laser beam and produced a Fraunhofer diffractionpattern used to infer the particle size distribution.

The geometric diameter emitted from the breath activated inhaler wasmeasured using an IHA accessory (Sympatec) with the HELOS laserdiffractometer. The IHA adapter positions the DPI in front of themeasuring zone and allows air to be pulled through the DPI to aerosolizethe powder. Vacuum was drawn at 30 L/min to disperse powder from the AIRinhaler and the geometric diameter was measured by Fraunhoferdiffraction.

The primary aerodynamic diameter was measured using an AeroDisperser/Aerosizer (TSI Inc., Amherst, Mass.). The sample powder was aerosolizedby an inlet air stream at 1 psi in the AeroDisperser and thenaccelerated to sonic velocity into the Aerosizer. The Aerosizer measuresthe time taken for each particle to pass between two fixed laser beams,which is dependent on the particle's inertia. The TOF measurements weresubsequently converted into aerodynamic diameters using Stokes law.

The emitted aerodynamic diameter from the AIR inhaler was determinedusing the AeroBreather (TSI Inc., Amherst, Mass.) in conjunction withthe Aerosizer (TSI, Inc.) The powder was aerosolized from the inhaler at30 L/min into the AeroBreather chamber and allowed to settle into theAerosizer.

Using these techniques, the inventors compared the primary size from thedry powder disperser at 4 bar to the emitted size from the AIR inhalerat 30 L/min (FIG. 2A). As can be seen, the spray dried hGH and spraydried albuterol sulfate emitted particle size was almost identical totheir measured primary particle size, which is not the case for themicronized albuterol sulfate. Finally, the inventors also measuredprimary and emitted aerodynamic size for the spray dried albuterolsulfate and compared it to the micronized albuterol sulfate (FIG. 2B).Again, the spray dried albuterol sulfate emitted with a nearly identicalaerodynamic diameter as its primary particles' aerodynamic diameterwhile the micronized albuterol sulfate emitted with a much largeraerodynamic diameter than its primary particles' aerodynamic diameter.This further confirms that the spray dried powders of the presentinvention disperse into respirable particles while the micronized drugremains nonrespirable even though its primary size is respirable.

The results of this example demonstrate that using the methods of theinstant invention, Applicants achieved high-efficiency delivery from asimple breath-activated device by loading it with powder that is highlydispersible.

Example 2

To illustrate that a highly dispersing powder can efficiently emit andpenetrate into the lungs from a range of breath-activated dry powderinhalers (DPIs), Applicants prepared a spray-dried powder comprised ofsodium citrate, DPPC, calcium chloride buffer, and a trace amount of arhodamine fluorescent label. The powder possessed a median aerodynamicdiameter of 2.1 μm (measured by the AeroDisperser and Aerosizer) and ageometric diameter of 11.0 μm (measured using the RODOS/HELOS) anddisplayed excellent deaggregation properties similar to the spray-driedpowders in Example 1.

Applicants placed 5 mg of the powder in the capsules using asemi-automated capsule filling device in the following inhalers: abreath activated inhaler under development by the applicant AIR Inhaler,the Spinhaler® (Fisons, Loughborough, U.K.), Rotahaler® (Glaxo-Wellcome,RTP, NC), FlowCaps® (Hovione, Loures, Portugal), Inhalator®(Boehringer-Ingelheim, Germany), and the Aerolizer® (Novartis,Switzerland). Applicants also tested the Diskhaler (Glaxo-Wellcome, RTP,NC), for which 3 mg of the powder was machine-filled into the blisterpacks. Applicants connected each inhaler to a collapsed Andersen cascadeimpactor (consisting of stage 0 and the filter stage,) and extracted airat 60 L/minutes for 2 seconds after actuating the device. The fineparticle fraction less than stage 0, having a 4.0 μm cut-off, wasdetermined using fluorescent spectroscopy.

FIG. 3 shows the results from the study. Applicants found that in eachcase, approximately 50% or more of the emitted dose displays a meanaerodynamic diameter (Da) less than 4 μm in size, indicating that thepowder efficiently would enter the lungs of a human subject at aphysiological breath rate, despite the simplicity of thesebreath-activated devices. Applicants also demonstrated that using themethods of the instant invention, large percentages of a nominal dose atlow energy were emitted from not only single dose, breath-actuatedinhalers but also from a range of breath-actuated dry powder inhalers(DPIs).

Example 3

A human deposition study was performed to determine whether a highlydispersible powder emitted from a simple breath-actuated inhaler couldproduce highly efficient delivery to the lungs (>50% of the nominaldose). Powders possessing the following characteristics were used:Dg=6.7 μm; ρ=0.06 g/cc; Da=1.6 μm.

The powder was labeled with ^(99m)Tc nanoparticles.

Human Deposition Studies

Gamma scintigraphy is an established methodology for assessing thepattern of deposition of inhaled particles. In this example the testsubstance is labelled with a small dose of the radioisotope ^(99m)Tc atthe InAMed laboratories (Gauting, Germany). Determination of the lungborder is enhanced by undertaking an ^(Blm) Kr ventilation scan.Inspiratory flow rates were monitored to ensure that a deep, comfortableinhalation has been performed during the deposition study. The range ofpeak inspiratory flow rates (PIFR) for a deep comfortable inhalationthrough the breath activated inhaler was assessed prior to study start.PIFRs outside the specified range will be repeated.

Studies were performed in 10 normal subjects A baseline ventilation scanwas undertaken to assist definition of the lung borders. Lung functionwas assessed before and after each test inhalation. Deposition wasdetermined following inhalation by gamma scintigraphy. Inspiratory flowrates through a breath activated inhaler were monitored during thedeposition using a spirometer.

Subjects were trained to inhale through a breath activated inhaler witha deep, comfortable inhalation. Subjects were trained to achieve a peakinspiratory flow rate (PIFR) through a breath activated inhaler within aspecified range representing a deep, comfortable inhalation. The breathactivated inhaler was actuated and attached to the spirometer to monitorthe inspiratory flow rate during the deposition study. The subject tooka capsule from the appropriate box, according to the predeterminedrandornisation schedule, and placed it in the inhaler/spirometer deviceimmediately prior to use.

Each subject was relaxed and breathing normally (for at least 5breaths). The inhaler mouthpiece is placed in the mouth at the end of anormal exhalation. The subject inhaled through the mouth with a deep,comfortable inhalation until the lungs are full. The subject then heldtheir breath for approximately 5 seconds (by counting slowly to 5).Deposition was measured in the gamma camera immediately afterexhalation. A further lung function test was then performed using aJaeger body plethysmograph, (Jaeger, Wurzburg, Germany).

Materials and Methods

The placebo powder, comprised of 70/20/10% w/w DPPC/SodiumCitrate/Calcium Chloride, which was used had the followingcharacteristics: Dg=6.7 μm; p=0.06 g/cc; Da=1.6 μm. The primaryaerodynamic particle size characteristics were obtained usingtime-of-flight (AeroSizer/AeroDisperser) and the geometric particle sizecharacteristics using laser diffraction (RODOS/HELOS) operated at 1 and2 bar. Emitted aerodynamic particle size characteristics were obtainedusing Andersen cascade impaction (gravimetric analysis) operated at 28.3L/min, for a total air volume of 2 L. Geometric particle sizecharacteristics were obtained using laser diffraction (IHA/HELOS,Sympatec, N.J.) operated at 60 L/min.

Powder Radiolabeling

Placebo powder was filled in a reservoir which was closed by an 0.2 μmfilter. A ^(99m)Tc solution (0.5 ml ^(99m)Tc in isotonic saline added to100 ml of deionized water) was filled in a Pari Jet nebulizer which wasplaced in a drying chamber. The Pari Jet nebulizer was activated for 3min to nebulize 1.5 ml of the ^(99m)Tc solution. The particles weredried in this'chamber and led through the reservoir containing thepowder. The humidity in the labelling chamber was controlled and neverexceeded 30% relative humidity.

Because of the short half life of the ^(99m)Tc, the labelling wasperformed 2-4 hours before the inhalation. The activity of the powderwas corrected for the physical decay of the Technetium, to get theactual activity which was available at the beginning of the inhalation.

The emitted aerodynamic particle size distribution of the post-labeledpowder was obtained using an 8-stage Andersen cascade impactor(gravimetric analysis) to verify that the radiolabeling process did notaffect the particle size distribution.

Size 2 capsules were hand filled with 5(±1) mg of the radiolabeledpowder. Each capsule was numbered and its filled weight and level ofradioactivity were recorded. The subject took a capsule and placed it inthe inhaler/spirometer device immediately prior to use.

Methodology for the Determination of Powder in the Regions of the Lung

The inhalation of the labelled porous particles was performed while thesubject was sitting with his back against the gamma camera. Afterinhalation a gamma scintigraphic image was taken while the subject wassitting upright with their back in front of the camera. The inhalationtime and breath holding period was recorded. The size of the lungs wasdetermined by an ⁸¹Kr scan. This radioactive gas was inhaled by thesubject before or at the end of the study.

From the Krypton ventilation scan of the subject the outline of thelungs was taken. Because the subject was sitting in the same position atthe Krypton scan and the powder inhalation there were 4 regions ofinterest (ROI) that were defmed: left lung, right lung, stomach andoropharynx (including upper part of trachea).

These 4 ROIs were copied to the gamma camera image of the powderinhalation. In a region outside of the subject's lung, the backgroundactivity was defined and subtracted pixel by pixel from the entireimage. Then the number of counts was determined for the 4 ROIs. Thesenumbers were corrected by an attenuation factor for the single regions.After this correction, the relative amount of intrathoracic versusextrathoracic particle deposition was determined.

Equivalence between the mass and gamma radiation particle sizedistributions was obtained, as shown in FIG. 4. Approximately 5 mg ofpowder was loaded into size 2 capsules. The capsules were placed into abreath activated inhaler under development by the applicant (AIRinhaler) and then the inhaler was actuated. Ten healthy subjects inhaledthrough an inhaler at an approximately inspiratory flow rate of 60L/min. (The actual insμmatory flow rate varied from subject to subjectover a range of 20 to 90 L/min., consistent with the normal range ofinspiratory flow rates in humans). 60 L/min is a good average flow rateand is what is used experimentally to mimic inspiratory flow. Asmeasured by a spirometer, the deposition image was obtained using agamma camera. The percentage lung deposition (relative to the nominaldose) obtained from the ten subjects is shown in FIG. 5. The averagelung deposition relative to the nominal dose was 59.0%.

Through this experiment, the Applicants confirmed that highlydispersible powder comprising drug can be inhaled into the lungs withhigh efficiency using a simple breath-actuated inhaler.

Example 4

To demonstrate that the same preparations of a highly dispersing powderthat had excellent aersolization properties from a simple inhaler can beused to deliver a surprisingly high dose in single inhalation,Applicants prepared a highly dispersible powder and loaded the powder toobtain a large pre-metered dose (50 mg) and a smaller pre-metered dose(6 mg). The particle size characteristics of the powder were asfollows:Dg=10.6 μm; ρ=0.11 g/cc; Da=3.5 μm

The aerodynamic particle size distributions were characterized using amultistage liquid impinger (MSLI) operated at 60 L/min. Size 2 capsuleswere used for the 6 mg dose and size 000 capsules were used for the 50mg dose. FIG. 6 shows the results comparing the two particle sizedistributions obtained for the 6 and 50 mg doses. The fine particlefraction, <6.8 μm relative to the total dose (FPF_(TD)<6.8 μm), for the6 and 50 mg doses were 74.4% and 75.0%, respectively.

This experiment demonstrated that a surprisingly large dose of drug canbe delivered to the lungs with equal efficiency as a small drug dose bycombining the properties of a highly dispersible powder with the methodsof the instant invention.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A method of delivering a therapeutic dose of a bioactive agent to the pulmonary system of a subject, in a single, breath-activated step, comprising: administering particles comprising a bioactive agent, from a receptacle having a mass of particles, to a subject's respiratory tract, wherein: i) the particles administered to the subject's respiratory tract have a tap-density of less than 0.4 g/cm³; ii) at least 75% of the particles have a fine particle fraction less than 6.8 μm and iii) at least about 50% of the mass of particles stored in the receptacle is delivered to the pulmonary system of the subject.
 2. The method of claim 1 wherein the particles have a tap density of less than about 0.1 g/cm³.
 3. The method of claim 1 wherein the particles have a geometric diameter greater than about 5 μm.
 4. The method of claim 1 wherein the receptacle has a volume of at least about 0.37 cm³.
 5. The method of claim 1 wherein the receptacle has a volume of at least about 0.48 cm³.
 6. The method of claim 1 wherein the receptacle has a volume of at least about 0.67 cm³.
 7. The method of claim 1 wherein the receptacle has a volume of at least about 0.95 cm³.
 8. The method of claim 1 wherein delivery is primarily to the deep lung.
 9. The method of claim 1 wherein delivery is primarily to the central airways.
 10. The method of claim 1 wherein the bioactive agent is albuterol sulfate.
 11. The method of claim 1 wherein the bioactive agent is insulin.
 12. The method of claim 1 wherein the bioactive agent is growth hormone.
 13. The method of claim 1 wherein the bioactive agent is fluticasone.
 14. The method of claim 1 wherein the bioactive agent is salmeterol.
 15. The method of claim 1 wherein the bioactive agent is a hydrophobic drug.
 16. The method of claim 1 wherein the bioactive agent is a hydrophilic drug.
 17. The method of claim 1 wherein the bioactive agent is a monoclonal antibody.
 18. The method of claim 1 wherein the particles are in the form of a dry powder.
 19. The method of claim 1 wherein administration to the respiratory tract is by a dry powder inhaler.
 20. A method of delivering a therapeutic dose of a bioactive agent to the pulmonary system of a subject, in a single breath, comprising: administering dry powder particles comprising a bioactive agent, from a receptacle having a mass of particles, to a subject's respiratory tract in a single breath, wherein: i) the particles have a tap density less than about 0.4 g/cm³; ii) at least about 5 milligrams of the bioactive agent is delivered to the pulmonary system of the subject and iii) at least 75% of the particles have a fine particle fraction less than 6.8 μm.
 21. The method of claim 20 wherein the particles have a tap density of less than about 0.1 g/cm³.
 22. The method of claim 20 wherein the particles have a geometric diameter greater than about 5 μm.
 23. The method of claim 20 wherein the receptacle has a volume of at least about 0.37 cm³.
 24. The method of claim 20 wherein the receptacle has a volume of at least about 0.48 cm³.
 25. The method of claim 20 wherein the receptacle has a volume of at least about 0.67 cm³.
 26. The method of claim 20 wherein the receptacle has a volume of at least about 0.95 cm³.
 27. The method of claim 20 wherein the particles deliver at least 15 milligrams of the bioactive agent.
 28. The method of claim 20 wherein the particles deliver at least 20 milligrams of the bioactive agent.
 29. The method of claim 20 wherein the particles deliver at least 30 milligrams of the bioactive agent.
 30. The method of claim 20 wherein the particles deliver at least 35 milligrams of the bioactive agent.
 31. The method of claim 20 wherein the particles deliver at least 50 milligrams of the bioactive agent.
 32. The method of claim 20 wherein delivery is primarily to the deep lung.
 33. The method of claim 20 wherein delivery is primarily to the central airways.
 34. The method of claim 20 wherein the bioactive agent is albuterol sulfate.
 35. The method of claim 20 wherein the bioactive agent is insulin.
 36. The method of claim 20 wherein the bioactive agent is growth hormone.
 37. The method of claim 20 wherein the bioactive agent is ipratropium bromide.
 38. The method of claim 20 wherein the bioactive agent is fluticasone.
 39. The method of claim 20 wherein the bioactive agent is salmeterol.
 40. The method of claim 20 wherein the bioactive agent is a hydrophobic drug.
 41. The method of claim 20 wherein the bioactive agent is a hydrophilic drug.
 42. The method of claim 20 wherein the bioactive agent is a monoclonal antibody.
 43. The method of claim 20 wherein the particles are in the form of a dry powder.
 44. The method of claim 20 wherein administration to the respiratory tract is by a dry powder inhaler.
 45. The method of claim 1 wherein at least 50% of the particles have a fine particle fraction less than 4.0 μm.
 46. The method of claim 20 wherein at least 50% of the particles have a fine particle fraction less than 4.0 μm.
 47. The method of claim 1 wherein said particles are spray dried particles.
 48. The method of claim 20 wherein said particles are spray dried particles.
 49. The method of claim 20 wherein the particles deliver at least 10 milligrams of the bioactive agent. 